1. Field of the Invention
The present invention relates generally to an electronic device, a mathematical expression display control method, etc., which control cursor movement at a time of inputting a mathematical expression.
2. Description of the Related Art
Conventionally, in most of electronic calculators which are called “scientific calculators”, a mathematical expression, which is key-input by a user, or a calculation result of the mathematical expression is displayed in one line as such.
In recent years, there have been scientific calculators which adopt “mathematically natural display” in which a mathematical expression is displayed in such a natural form as described in school textbooks, etc. Since the “mathematically natural display” is a mode as described in school textbooks, etc., this mode is easy to understand and convenient even in a case of a complex mathematical expression.
On the other hand, compared to one-line display adopted in conventional scientific calculators, the “mathematically natural display” tends to become cumbersome and complex since the input and edit of a mathematical expression involves a greater number of steps. For example, in an “integral function” of a special arithmetic operation, there are three input positions, namely a numerical expression part, an infimum part and a supremum part, and a plurality of numerical expression constituents (e.g. a numeral, a variable, an arithmetic sign, etc.) can be input to each position. Thus, in the case where a plurality of numerical expression constituents were input to each of the numerical expression part, infimum part and supremum part, multiple-time operations for cursor movement need to be performed in each of the numerical expression part, infimum part and supremum part, in order to move the cursor in the mathematical expression. In addition, in the case of moving the cursor from the inside of the numerical expression of the “integral function” to an outside numerical expression part, the cursor has to move via the respective numerical expression constituents, i.e. the numerical expression part, infimum part and supremum part, and the number of times of operation for cursor movement becomes larger.
Besides, in a special arithmetic operation such as “integral function”, for example, numerical expression constituents are input in the order of the numerical expression part, infimum part and supremum part in accordance with a mathematical rule. Thus, the cursor is also moved in the order corresponding to the mathematical rule, in association with the operation of moving the cursor in a certain direction. For example, if an operation of moving the cursor to the right is repeated when the cursor is present in the numerical expression part, the cursor is moved to the infimum part positioned on the left side of the numerical expression part, that is, to the left.
Conventionally, a technique has been thought in which, in the case where a function expression of a special arithmetic operation, such as “integral function”, is displayed, an optimal movement destination corresponding to a current cursor position in a numerical expression is searched in accordance with an instruction to move the cursor, and the cursor is moved to the optimal movement destination (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-264765).